1. Field of the Invention
The present invention relates generally to immunoassay test methods and devices and more particularly to radioimmunoassay test methods and devices.
2. Description of the Prior Art
Many radioimmunoassay test methods and devices have been developed since the pioneering work of Ekins in 1960 and Yalow and Berson in 1960. The standard method for conducting radioimmunoassays, as described by these pioneering researchers, is based upon a theory of competitive binding. Such a test method for a particular antigen of interest, utilizing competitive binding principals, requires an antibody which is specific to the antigen and a quantity of radiolabeled antigen. Liquids containing the unknown antigen and the radiolabeled antigen are reacted with the antibody, and both the unknown antigen molecules and the radiolabeled antigen molecules compete for the binding sites of the antibody molecules. The competitive immunoreaction is conducted until near-equilibrium conditions have been achieved between the bound and unbound reactants. Thereafter, the antibody bound antigen is separated from the liquid reactants by any of several means. Following the separation, the radioactivity of the antibody bound antigen is determined. Further tests are thereafter conducted utilizing a plurality of liquids containing differing known concentrations of the antigen and after equilibrium conditions have been achieved in each of the immunoreactions, the antibody with the bound radioactive antigen from each of such reactions is examined for its radioactivity. Thereafter, a calibration curve is created which correlates the radioactivity from the immunoreactions utilizing known samples with the concentration of antigen in the known samples. Finally, using the calibration curve and the radioactivity of the unknown antigen immunoreaction the concentration of antigen in the unknown sample is determined.
Testing devices, commonly known as test kits, which utilize the above-described competitive binding test method typically contain a quantity of radiolabeled antigen of interest, a quantity of antibody in a form suitable for accomplishing the separation thereof from the liquid reactants, and quantities of each of several different liquids, each having a differing known concentration of the antigen of interest. It is to be realized that due to the slow degradation of the antibody and the decay of the radiolabeled antigen that each time a researcher desires to utilize the test kit, a new calibration curve must be created utilizing each of the several liquids having the differing known concentrations of antigen. Additionally, for each such test, the researcher must conduct the immunoreactions until near-equilibrium conditions exist in the reactions. Such equilibrium conditions typically take thirty minutes or more to be established and some may take up to several days. Thus, immunological testing utilizing the competitive binding test method currently requires a significant amount of time, at least thirty minutes, and the creation of a new calibration curve for each series of test determinations.